09 June 2022
Cooling of new buildings and tree canopies are essential during heat waves

British Columbia’s efforts to prevent mass deaths during its next heat wave will accelerate the multiple moves already happening in many cities to ensure that all new buildings have robust ventilation and to add tree canopy that provides cooling shade, say those working in park planning and building.

But some of those improvements will be harder to speed up than others, they say, as everyone looks at the recommendations from the BC Coroners Service heat-dome report out Tuesday. That report said the province should amend the building code to require active and passive cooling in all new houses by 2024 and that cities should ensure they are protecting their tree canopy.

Mechanical equipment to provide either air conditioning or cooling through heat pumps is already in short supply, after cities like Vancouver and North Vancouver have moved ahead of the already-climate-focused B.C. Building Code to require them now or within a few years, said Ron Rapp, chief executive of the province’s home builders’ association, HAVAN. And cities might even run into problems with enough electrical supply to power all the new cooling devices.

“It’s going to be a challenge in many aspects,” said Mr. Rapp. “There needs to be a realistic look at capacities.”

On the tree front, Vancouver’s park board has a goal of increasing the city’s tree canopy – a green parasol that can reduce a street’s temperature by 10 to 15 degrees – to 30 per cent from its current 23 per cent.

But it takes many years to grow a tree to the size where it provides real protection, so that goal is set for 2050. In the meantime, park staff have to compete with many other demands for precious space in Vancouver to get spots with enough dirt to support large trees.

“Big trees provide the greatest amount of environmental service but there are few places left for trees except the street right-of-way,” said Dave Hutch, the board’s director of planning and park development.

The park board is also constantly trying to add park space – something that was heavily used during the heat wave by people escaping their hot homes – to keep up with its standard of about two hectares per 1,000 people. But the price of land makes that difficult.

The province was already making moves to change its building code and its programs for retro-fitting homes. This wasn’t only to emphasize energy efficiency, but also to recognize the fact that temperate B.C. will need to deal with building homes – not just for the cold but also for heat, said Alex Boston, executive director of Simon Fraser University’s Renewable Cities program who sat on the panel that advised the coroners service.

The CEO of the province’s Urban Development Institute, which represents many of B.C.’s biggest builders, concurred that a lot has happened already in terms of requirements for cooling in buildings.

Anne McMullin said a recent report on B.C. cities indicated that almost all new condos and the majority of new rentals, whether private or government-funded, are being built with mechanical cooling. And Vancouver’s requirement that all new homes incorporate heat pumps will automatically mean cooling is built in, since the pumps perform both functions.

But B.C. is much further behind on requiring cities to develop better land-use practices, Mr. Boston said. The province was supposed to be getting cities to update their development plans with a “climate lens,” but that effort has fallen behind. As a result, two of the key pieces of heat mitigation – tree canopy and green space – have not had much attention.

Mr. Boston noted that a third of the 619 people who the coroners service said had died of heat-related causes last June lived in single-family homes – evidence that mortality isn’t a function of high- or low-density housing. Instead, it’s issues such as poor ventilation, building materials that retain heat and high neighbourhood temperatures from lack of tree canopy, along with many others, including pre-existing health conditions and social isolation.

Tree canopy has become a preoccupation in several Metro Vancouver cities, as development either gets more intense in already built-up areas or it spreads out to previously undeveloped land. Mr. Boston noted that the region is losing about 6,500 hectares a year of green space as homes and commercial enterprises are built in what were fields, farms or forests.

In Vancouver, the city experimented with allowing a simpler process for dealing with trees during development but staff recommended this week that it revert to the previous process, which requires extensive vetting by the landscape department, after reporting that 640 trees had been removed in a single year of the pilot.

Mr. Boston said that, while multifamily developments throughout the region are often required to install significant amounts of greenery, single-family developments sometimes result in cleared land that is then partly covered by asphalt.



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